The structure of the Government of Ireland is regulated fundamentally by the Constitution of Ireland. The Government is headed by a prime minister called the Taoiseach. The deputy prime minister is called the Tánaiste, and is nominated by the Taoiseach from among the members of the Government.

The Government must consist of between seven and fifteen members, according to the Constitution of Ireland.[1] Every member of the Government must be a member of the parliament of Ireland, called the Oireachtas. No more than two members of the Government may be members of Seanad Éireann, the upper house of the Oireachtas.[2] Therefore, all other members of the Government must be members of Dáil Éireann, the lower house. The Taoiseach, Tánaiste and Minister for Finance must be members of the Dáil.[3] The 7 to 15 Members of Government are generally referred to as "The Cabinet".

The Taoiseach is nominated by Dáil Éireann, the lower house of the Oireachtas, and appointed by the President. Other members of the Government are nominated by the Taoiseach, approved by Dáil Éireann, and appointed by the President. Members of the government are often styled "cabinet ministers", as opposed to Ministers of State (before 1977 Parliamentary Secretaries), called "junior ministers", who are not in the cabinet. A minister is usually in charge of a Department of State and thus technically a "Minister of the Government" (before 1977 a "Minister of State").[4] Occasionally a minister without portfolio is appointed who is a minister and a member of the Government but not a "Minister of the Government".

Non members have no voting rights at Cabinet but may otherwise participate fully and normally receive circulated Cabinet Papers on the same basis as a full member of Government.

The Government is advised by the Attorney General, who is not formally a member of the Government, but who participates in cabinet meetings as part of her role as legal advisor to the Government.

The Chief Whip may attend meetings of the cabinet, but is not a member of the Government.[5]

In addition, the Government can choose other Ministers of State (junior minister), who may attend cabinet meetings. This person is informally known as a Super Junior Minister".[5] The current (2016) Super Junior Ministers are Paul Kehoe and Finian McGrath.

The President of Ireland is not a member of the government. The Constitution of Ireland does not make the President the nominal chief executive officer of the government, instead it explicitly vests executive authority in the cabinet. In addition, the President does not have discretion in appointing a Taoiseach; this is a constitutional obligation which must happen upon the nomination of the Taoiseach. A similar obligation exists for the appointment of members of the Government; they must be appointed upon nomination by the Taoiseach and approval by the Dáil.

Normally, the Government serves in office until the nomination of a new Taoiseach by Dáil Éireann.

The Government must enjoy the confidence of Dáil Éireann if it is to remain in office. If the Taoiseach ceases "to retain the support of a majority in Dáil Éireann", either Dáil Éireann must be dissolved or the Taoiseach must resign.[6] The President may refuse to grant a dissolution to a Taoiseach who does not enjoy the support of the Dáil, thus forcing the resignation of the Taoiseach.

When the Taoiseach resigns, the entire Government is deemed to have resigned as a collective. However, in such a scenario, according to the Constitution, "the Taoiseach and the other members of the Government shall continue to carry on their duties until their successors shall have been appointed". The Taoiseach can also direct the President to dismiss or accept the resignation of individual ministers.

Upon the dissolution of Dáil Éireann, ministers are no longer members of the Oireachtas, and therefore ineligible for office. However, under a different clause in the Constitution, they "shall continue to hold office until their successors shall have been appointed".[7]

The Constitution explicitly vests executive authority in the Government, not the President. In other parliamentary regimes, the head of state is usually the nominal chief executive, though bound by convention to act on the advice of the cabinet.

The executive authority of the Government is subject to certain limitations. In particular:

The state may not declare war, or participate in a war, without the consent of the Dáil Éireann. In the case of "actual invasion", however, "the Government may take whatever steps they may consider necessary for the protection of the State"[8]

Government ministers are collectively responsible for the actions of the government. Each minister is responsible for the actions of his or her department. Departments of State do not have legal personalities. Actions of departments are carried out under the title of ministers even, as is commonly the case, when the minister has little knowledge of the details of these actions. This contradicts the rule in common law that a person given a statutory power cannot delegate that power.[9] This leads to a phrase in correspondence by government departments, "the Minister has directed me to write", on letters or documents that the minister in question may never have seen.

If the Government should fail to fulfill its constitutional duties, it may be ordered to do so by a court of law, by writ of mandamus. Ministers who fail to comply may, ultimately, be found to be in contempt of court, and even imprisoned.

All Governments since 1989 have been coalitions of two or more parties. The first coalition government was formed in 1948. The Taoiseach has always been a member of the largest party in the coalition. The Taoiseach has almost always been the leader of that party, with John A. Costello the only exception to this rule.

The Government is a significant employer in the state, because of its control of the civil service, the public service, and the state-sponsored bodies. These three sectors are often called the "public sector". These bodies are managed in different ways. The civil service features clearly defined and standard hierarchies of management, while among the public services, a sponsoring minister or the Minister for Finance may appoint a board or commission. The state's commercial activities are normally managed through the state-sponsored bodies, which are organised in a similar fashion to private companies.

A June 2005 report on public sector employment,[11] shows that the numbers employed in the public sector stood at 350,100. By sector, there were 38,700 in the civil service, 254,100 in the public service and 57,300 in state-sponsored bodies. The total workforce of the state was 1,857,400 that year. Thus, the public sector comprised approximately 20% of the total workforce.

The civil service of Ireland consists of two broad components, the Civil Service of the Government and the Civil Service of the State. While this partition is largely theoretical, the two parts do have some fundamental operational differences. The civil service is expected to maintain political impartiality in its work, and some parts of it are entirely independent of Government decision making.

The public service is a broad term, not clearly defined, and it is sometimes taken to include the civil service. The public service proper comprises Government agencies and bodies which provide services on behalf of the Government, but which are not part of the civil service. For instance, local authorities, Education and Training Boards and the Garda Síochána are considered to be public services.